Risk of neurological injury in posterior bone block surgery for recurrent glenohumeral instability: a cadaveric study.

INTRODUCTION: Recurrent posterior glenohumeral instability poses a challenge for treatment. Bone block procedures have been advocated in cases where a bony defect is present. However, these techniques are not free of complications due to the proximity of neurovascular structures. The aim of this study is to measure the distance to the axillary and suprascapular nerves at the different steps of the procedure. MATERIALS AND METHODS: Ten frozen human cadavers were used. The bone graft was prepared and placed on the posterior aspect of the glenoid, where it was fixed with two K-wires in different positions: parallel to the articular surface and with 20° of medial angulation. The distance from the entry and exit points of the K-wires to the axillary and suprascapular nerves was measured. RESULTS: At the exit point, mean distance from the superior K-wire to the axillary nerve was 4.4 mm in the neutral position and 14.4 mm when medially angulated (p = 0.01) and 2.6 mm and 11.5 mm, respectively, for the inferior K-wire (p < 0.01). No differences were found at the entry point (p = 0.7 and p = 0.3). For the suprascapular nerve, mean distance to the entry point of the superior K-wire was significantly greater when it was inserted with 20° of medial angulation than when placed in neutral position (p = 0.04). No differences were found for the inferior K-wire (p = 0.35). CONCLUSION: Posterior bone block surgery should be performed taking into consideration the possibility of axillary nerve injury anteriorly at the exit point of the K-wires. Wire and screw insertion parallel to the glenoid articular surface may reduce the risk, while increased wire or screw medial angulation with respect to the glenoid surface may heighten risk. LEVEL OF EVIDENCE: Not applicable (cadaveric study).

Clinical outcome and prognostic factors of revision arthroscopic rotator cuff tear repair.

PURPOSE: The aim of this study was to evaluate the clinical outcome of arthroscopic rotator cuff revision surgery in a cohort of patients and to identify prognostic factors for this procedure. METHODS: Fifty-one consecutive patients undergoing revision arthroscopic rotator cuff repair were prospectively followed over a minimum period of one year. Radiologic findings and clinical data regarding primary and revision surgery were collected. Clinical evaluation was performed pre- and post-operatively by means of Constant Score and Simple Shoulder Test. RESULTS: Median age at the time of revision surgery was 60 years (range 36-77 years). Median follow-up was 25 months (range 12-58 months). There were 17 men (33.3%) and 34 women (66.7%). The majority of the tears affected the supraspinatus tendon alone (51%) or both the supra- and infraspinatus tendons (35.3%). Significant improvements were seen in terms of active forward elevation, active external rotation, pain, Simple Shoulder Test score, Constant Score, and post-operative satisfaction-age, gender, and time to revision surgery did not show significant predictive value. A smaller tear size and pre-operative elevation greater than 90° were demonstrated to be independent prognostic factors for better outcome. However, the mean increase in Constant Score was not related to the size of the tear, range of motion, or age. CONCLUSION: The results of this study indicate that arthroscopic revision rotator cuff repair results in reliable improvement in shoulder function, pain, and satisfaction. Pre-operative active range of motion and tear size seem to determine final outcome. A similar increase in mean Constant Score can be achieved even in large tears in patients aged over 65 years. LEVEL OF EVIDENCE: IV.

Surgical anatomical landmarks for arthroscopic repair of subscapularis tendon tears.

BACKGROUND: Subscapularis repair has recently garnered significant interest. A thorough understanding of the tendon's anatomy is essential for precise and safe repair. Our objectives were to describe the anatomy of the subscapularis insertion, define its landmarks, and analyze nearby structures to guide arthroscopic repair. METHODS: We conducted an anatomical study, dissecting 12 shoulders. We evaluated the distance from the footprint to the axillary nerve, the dimensions, and shape of the footprint, and its relationship with the humeral cartilage. RESULTS: The distance to the axillary nerve was 32 mm (standard deviation [SD], 3.7 mm). The craniocaudal length of the footprint was 37.3 mm (SD, 4.6 mm). Its largest mediolateral thickness was 16 mm (SD, 2.2 mm), wider at the top and narrower distally. The distance between the footprint and the cartilage varied, being 3.2 mm (SD, 1.2 mm) in the upper part, 5.4 mm (SD, 1.8 mm) in the medium, and 15.9 mm (SD, 2.9 mm) in the lower part. CONCLUSIONS: When performing a repair of the subscapularis tendon, the distance to the cartilage should be carefully evaluated as it varies proximally to distally, and the shape of the footprint (wider proximally, tapered distally) should be considered for implant positioning. The distance to the axillary nerve is approximately 30 mm. Anterior visualization guarantees direct control of all landmarks and allows accurate implant positioning with safe tendon release. Level of evidence: IV.

Management of Humeral Defects in Anterior Shoulder Instability.

BACKGROUND: A Hill Sachs lesion is a posterior-superior bony defect of the humeral head caused by a compression of the hard glenoid rim against the soft cancellous bone in the context of an anterior instability episode. The presence of these humeral defects increases with the number of dislocations and larger lesions are associated with a greater chance of development of recurrent instability and recurrence after surgery. Also its location and pattern, in particular the so-called engaging Hill-Sachs, are associated with poor prognosis. METHODS: There is a lack of consensus in terms of classification and management algorithm, although lesions greater than 25% of the humeral head had been suggested to need more than a simple Bankart repair to avoid recurrence. The concept of glenoid track has turned the attention to location and shape and not only size of the humeral defect. Moreover, the glenoid bone loss is crucial when choosing a treatment option as it contributes to decrease the glenoid track as well. A thorough revision of treatment options has been performed. RESULTS: Numerous treatment options have been proposed including remplissage, glenoid or humeral head augmentation, bone desimpaction, humeral rotational osteotomy and arthroplasty. CONCLUSION: Humeral defects treatment should be individualized. Determination of size and location of the defect and its relation with glenoid track is mandatory to achieve satisfactory results.

Physical Exam and Evaluation of the Unstable Shoulder.

BACKGROUND: The clinical evaluation of the patient with shoulder instability can be challenging. The pathological spectrum ranges from the straightforward "recurrent anterior dislocation" patient to the overhead athlete with a painful shoulder but not clear instability episodes. Advances in shoulder arthroscopy and imaging have helped in understanding the anatomy and physiopathology of the symptoms. The aim of this general article is to summarize the main examination manoeuvres that could be included in an overall approach to a patient with a suspicion of instability. MATERIAL AND METHODS: In order to achieve the above-mentioned objective, a thorough review of the literature has been performed. Data regarding sensibility and specificity of each test have been included as well as a detailed description of the indications to perform them. Also, the most frequent and recent variations of these diagnostic tests are included. RESULTS: Laxity and instability should be considered separately. For anterior instability, a combination of apprehension, relocation and release tests provide great specificity. On the other hand, multidirectional or posterior instability can be difficult to diagnose especially when the main complain is pain. CONCLUSION: A detailed interview and clinical examination of the patient are mandatory in order to identify a shoulder instability problem. Range of motion of both shoulders, clicking of catching sensations as well as pain, should be considered together with dislocation and subluxation episodes. Specific instability and hyperlaxity tests should be also performed to obtain an accurate diagnosis.

Acute Pectoralis Major Rupture Captured on Video.

Pectoralis major (PM) ruptures are uncommon injuries, although they are becoming more frequent. We report a case of a PM rupture in a young male who presented with axillar pain and absence of the anterior axillary fold after he perceived a snap while lifting 200 kg in the bench press. Diagnosis of PM rupture was suspected clinically and confirmed with imaging studies. The patient was treated surgically, reinserting the tendon to the humerus with suture anchors. One-year follow-up showed excellent results. The patient was recording his training on video, so we can observe in detail the most common mechanism of injury of PM rupture.

All-Suture Transosseous Repair for Rotator Cuff Tear Fixation Using Medial Calcar Fixation.

We describe an all-suture transosseous repair technique used in the management of rotator cuff tears by means of an all-suture anchor secured on the intra-articular side of the humeral calcar. The technique uses an anterior cruciate ligament guide to ensure accurate positioning of the tunnels, avoiding the articular cartilage and minimizing risk to the neurovascular structures. The distal end of the guide is inserted through a rotator interval portal and passed down to the axillary pouch. The proximal end of the guide is approximated to the greater tuberosity at the cuff footprint, and a complete transosseous tunnel is created with a 2.4-mm drill. An all-suture implant is inserted through this tunnel down to the calcar, and its deployment is visualized under arthroscopy. Gentle traction is applied to the anchor, resulting in a 4-mm concertina of the suture anchor that rests opposed to the medial cortex. The major advantage of this technique is the fixation strength gained from the biomechanically superior cortical bone of the calcar. Furthermore, this method permits greater preservation of bone surface area at the level of the footprint for a larger tendon-to-bone healing surface. This technique also provides an excellent alternative in revision situations.

Stem cell therapy in the management of shoulder rotator cuff disorders.

Rotator cuff tears are frequent shoulder problems that are usually dealt with surgical repair. Despite improved surgical techniques, the tendon-to-bone healing rate is unsatisfactory due to difficulties in restoring the delicate transitional tissue between bone and tendon. It is essential to understand the molecular mechanisms that determine this failure. The study of the molecular environment during embryogenesis and during normal healing after injury is key in devising strategies to get a successful repair. Mesenchymal stem cells (MSC) can differentiate into different mesodermal tissues and have a strong paracrine, anti-inflammatory, immunoregulatory and angiogenic potential. Stem cell therapy is thus a potentially effective therapy to enhance rotator cuff healing. Promising results have been reported with the use of autologous MSC of different origins in animal studies: they have shown to have better healing properties, increasing the amount of fibrocartilage formation and improving the orientation of fibrocartilage fibers with less immunologic response and reduced lymphocyte infiltration. All these changes lead to an increase in biomechanical strength. However, animal research is still inconclusive and more experimental studies are needed before human application. Future directions include expanded stem cell therapy in combination with growth factors or different scaffolds as well as new stem cell types and gene therapy.

Application of adipose tissue-derived stem cells in a rat rotator cuff repair model.

INTRODUCTION: Healing tissue of the rotator cuff does not regenerate the native enthesis; fibrovascular scar tissue is formed instead and this has less favourable biomechanical properties. The purpose of this study was to determine if the application of adipose tissue-derived stem cells (ASCs) could improve biomechanical and histological properties of the repair. MATERIAL AND METHODS: Fifty Sprague-Dawley rats underwent detachment and repair of the supraspinatus tendon, 32 for the biomechanical study and 18 for the histological examination. Animals were randomised in two groups to receive either a collagen carrier alone (untreated group) or the carrier plus 2×10(6) ASCs (ASCs group). A control group (suture only) was also included for the histological examination. The animals were sacrificed at 2 and 4 weeks for the biomechanical study and at 24 hours, and 1 and 4 weeks for the histological study. Maximum load failure energy, elastic energy, mechanical deformation, stiffness and absorbed energy were measured. Immunofluorescence testing was conducted to show the presence of ASCs in the repair area. RESULTS: There were no differences between the untreated group and the ASCs group in any of the biomechanical variables at the 2- and 4-week time points. The mechanical deformation before failure was higher for the ASCs group compared with the untreated group at 2 weeks and 4 weeks (p=0.09), as was the absorbed energy (p=0.06). Differences in maximum load to failure between 2 and 4 weeks were significant for the untreated group (p=0.04) but not for the ASCs group (p=0.17). Histological examination showed less acute inflammation with diminished presence of oedema and neutrophils in the ASCs group. There were no differences in the orientation of collagen fibres between groups at either time point. In the ASCs group, collagen was present only at the last time point. CONCLUSION: The application of ASCs in a rat rotator cuff repair model did not improve the biomechanical properties of the tendon-to-bone healing. However, the ASCs group showed less inflammation, which may lead to a more elastic repair and less scarred healing.